Powder feed arrangement for flame spray gun



c. K- WILSON 3,482,782

POWDER FEED ARRANGEMENT FOR FLAME SPRAY GUN Dec. 9, 1969 Filed Sept. 13.1967 INVENTOR CHARLES KENNETH WILSON ATTORNEYS.

FIG. 2.

United States Patent 3,482,782 POWDER FEED ARRANGEMENT FOR FLAME SPRAYGUN Charles Kenneth Wilson, Glen Head, N.Y., assignor to lg letco Inc.,Westbury, N.Y., a corporation of New ersey Filed Sept. 13, 1967, Ser.No. 667,454 Int. Cl. B05b 7/00; F23d 17/00 U.S. Cl. 239-85 9 ClaimsABSTRACT OF THE DISCLOSURE Flame spray gun with a remote powderreservoir and a conduit connecting the gun and the reservoir and meansfor conveying powder entrained in a carrier gas from the reservoirthrough the conduit to the gun having in combination therewith means atthe gun end of the conduit for separating the powder from the carriergas and feeding the separated powder directly into the gun thisarrangement preferably being in the form of a chamber mounted on the gunwith the conduit leading thereinto and which is provided with a gravitypowder outlet at its lower end leading into the gun and a gas exhaustfrom the chamber.

This invention relates to an improved powder feed arrangement for aflame spray gun. Powder type flame spray guns are well known and widelyused and, for example, are described in U.S. Patents 2,820,670 of Jan.21, 1958, and 2,961,335 of Nov. 22, 1960. The powder supply for powdertype flame spray guns, as for example shown in the above mentionedUnited States patents, is often maintained in a reservoir or hopperdirectly connected to the gun. This, however, limits the supply ofpowder available and may interfere with the manipulation and bandling ofthe gun.

It is also known to feed the powder to the gun from a remote reservoirthrough a conduit. The feeding of powder in this manner by gravity hasin most instances proven unreliable and it has generally become thepractice to feed the powder from the remote reservoir to the conduitentrained and carried by a carrier gas. The volume and velocity ofcarrier gas required for reliable transportation from the reservoirthrough the conduit to the gun is not, however, generally the optimumproportion of carrier gas for spraying. The conveying of the powder inthis carrier gas into and through the gun therefore often causesproblems in that the same may project the powder through the flame attoo high a velocity for efficient heating and the carrier gas mayundesirably cool the flame and/or cause a powder velocity through theflame at a rate other than that which favors optimum heating of thepowder particles by the flame.

One object of this invention is to avoid the above mentioneddisadvantage and to provide a reliable transportation of powder from aremote reservoir in a carrier gas to the flame spray gun whileeliminating the actual spraying disadvantages caused by the presence ofthe conveying carrier gas. This and still further objects will becomeapparent from the following description read in conjunction with thedrawings in which:

FIG. 1 is a side elevation partially in section showing a flame spraygun with a remote powder feeder provided with an embodiment of theinvention;

FIG. 2 is a vertical section showing a further embodiment of theinvention, and

FIG. 3 is a plan view of the device shown in FIG. 2.

The invention is applicable to any powder type flame spray gun having aremote powder reservoir, a conduit connecting the gun and reservoir, andmeans for conveying powder entrained in a carrier gas from the reservoirthrough the conduit to the gun. In accordance with the invention meansare provided at the gun end of the conduit for separating powder fromcarrier gas and feeding the separated powder directly into the gun. Themeans for separating the powder from the carrier gas preferablycomprises a powder-gas separating chamber mounted on the gun. Thischamber may have any known or conventional construction for separatingentrained powder particles from the gas and is most simply in the formof a chamber into which the powder and gas mixture are injected, thepowder being separated from the gas ballistically, by gravity,centrifugally, or the like, the separated carrier gas vented to theatmosphere and the powder gravity fed directly into the gun. While thechamber may accumulate the powder so separated, it has been foundpreferable if the same is constructed so that it feeds directly into thegun without accumulation. This can be most simply done by constructingthe gravity feed outlet so that the same will allow powder to flow outtherethrough by gravity at a higher rate than the maximum inlet rate ofthe carrier gas entrained powder.

Referring to the embodiment shown in the drawing I represents aconventional powder type flame spray gun having the construction asshown in U.S. Patents 2,820,670 and 2,961,335. The gun is provided witha remote powder reservoir which feeds powder entrained in a carrier gasthrough the conduit 3. The remote powder reservoir and feeder may, forexample, have the construction as described in U.S. Patent No. 3,138,298of June 23, 1964. In accordance with the invention, connected on top ofthe gun is the separating chamber 4. This separating chamber has acircular cross section and has an enlarged upper portion which conicallynarrows at its lower portion terminating with the gravity flow passage5. The

gravity flow passage leads through the conventional rubber tube pinchtype valve arrangement 6 into the feed passage 7 where powder flowing bygravity is picked up by a carrier gas flowing through the orifice 8 andis propelled to the nozzle 9 into the flame sheath emerging from thenozzle jet 10. The separating chamber 4 is provided with the cover 11which has the carrier gas vent 12. The conduit 3 is connected to aninlet pipe 13 which leads centrally into the chamber and which isdirected downwardly toward the gravity outlet passage 5. In. operationpowder entrained in a carrier gas is fed from the remote reservoir 2 inthe conventional manner through the conduit 3. The carrier gas entrainedpowder enters the separating chamber 4 through the inlet pipe 13 whereentrained powder is directed downwardly toward the flow passage 5 andballistically separates from the carrier gas which flows upwardly andout through the vent 12. The separated powder flows down through thepassage 5 through the valve 6 into the inlet 7 and out through thenozzle 9 without accumulating in the chamber 4. In all other respectsoperation of the gun is conventional and as is described in said U.S.patents.

The amount of and velocity of the carrier gas used to convey the powderto the reservoir 2 through the conduit 3 may be chosen for optimum andand reliable conveyance without being limited by the spraying conditionsand this carrier gas due to the separation from the powder in accordancewith the invention in no way influences the spraying or operation of thegun.

The separation of the powder from the carrier gas may be effected in anyknown or desired manner. In this embodiment shown in FIGS. 2 and 3 theinlet pipe 14 extends tangentially into the chamber 4 so that the powderwill be imparted a whirling motion and will centrifugally separate fromthe carrier gas with the chamber acting as a cyclone separator.

As mentioned, any other known or conventional separators may be used,including, for example, screen type separators, or simple gravityseparators in which the velocity of the gas is expanded by expansion,and/ or bafiles causing the powder to fall by gravity.

I claim:

1. In combination with a powder type flame spray gun having a remotepowder reservoir, a conduit connecting the gun and reservoir, and meansfor conveying powder entrained in a carrier gas from the reservoirthrough the conduit to the gun; means at the gun end of the conduit forseparating powder from carrier gas and feeding the separated powderdirectly into the gun.

2. Combination according to claim 1 in which said means for separatingpowder from carrier gas comprises a chamber mounted on the gun with saidconduit leading thereinto, a powder outlet at the lower end of thechamber and a gas exhaust from the chamber.

3. Combination according to claim 2 in which said powder outlet is agravity flow outlet at the bottom of said chamber and including a powderinlet to said chamber connected to said conduit and directed into anenlarged portion of said chamber toward said gravity flow outlet.

4. Combination according to claim 3 in which said flame spray gun has agravity feed powder inlet leading into a gas flow passage and in whichsaid gravity flow outlet forms a continuation of said gravity feedinlet.

5. Combination according to claim 2 in which said chamber narrows in adownward direction with said powder outlet at the lower end comprising agravity flow outlet, and including a powder inlet connected to saidconduit and tangentially leading into an enlarged upper portion of thechamber.

6. Combination according to claim 5 in which said gas exhaust comprisesa gas outlet opening from the upper portion of the chamber.

7. Combination according to claim 6 in which said flame spray gun has agravity feed powder inlet leading into a gas flow passage and in whichsaid gravity flow outlet forms a continuation of said gravity feedinlet.

8. In the method of conveying powder from a remote location to a flamespray gun in which the powder is conveyed through a conduit entrained ina carrier gas to the gun, the improvement which comprises separating thepowder and carrier gas at the gun and directly feeding the separatedpowder into the gun.

9. Method according to claim 8 in which the separated powder is directlygravity flowed into the gun.

References Cited UNITED STATES PATENTS 168,029 9/1875 Korting 302-59 X2,233,304 2/1941 Bleakley 239 X 3,129,889 4/1964 Cape 239-85 3,384,4205/1968 Fiscus 302-59 X FOREIGN PATENTS 106,235 1/ 1939 Australia.

EVERETT W. KIRBY, Primary Examiner MICHAEL Y. MAR, Assistant ExaminerUS. Cl. X.R.

